Latch timing mechanism for a two-step roller finger cam follower

Abstract

In a two-step roller finger cam follower, a slider arm for engaging a high-lift cam lobe is pivotally mounted to the body and can variably engage a latch pin slidably disposed in a latch pin channel. A second channel in the body opens onto the slider arm and contains a timing pin that rides on an eccentric surface of the slider arm to extend or retract the timing pin. A bore between the latch pin channel and the timing pin channel contains a ball controlled by the timing pin to lock the latch pin into an engaged or disengaged position. The cam lobe has an undercut region such that the latch pin is allowed to move between engaged and disengaged position only when the slider arm is in the undercut region of the cam lobe. The latch pin can move only when the timing pin permits.

Description

TECHNICAL FIELD[0001]The present invention relates to roller finger followers used for variable valve actuation in overhead cam type internal combustion engines, and more particularly to a variable actuation roller finger follower wherein a timing pin mechanism is disposed adjacent a latch pin such that the latch pin can engage with and disengage from a high-lift slider only when the slider is on a “negative lift” portion of the associated high-lift cam lobe.BACKGROUND OF THE INVENTION[0002]Roller finger followers (RFF) are widely used in overhead cam internal combustion engines to sequentially open and close the cylinder intake and exhaust valves. In a typical application, the RFF serves to transfer and translate rotary motion of a cam shaft lobe into a pivotal motion of the RFF to thereby open and close an associated valve.[0003]It is known that, for a portion of the duty cycle of a typical multiple-cylinder engine, the performance load can be met by a functionally smaller engine ...

AI Technical Summary

Benefits of technology

The patent describes a roller finger follower for use in internal combustion engines. The roller finger follower includes a body with a slider arm and a latch pin. A spring-biased timing pin is used to control the movement of the latch pin. The timing pin is forced by the slider arm when the latch pin is in the fully engaged position, and the latch pin can move between positions. The negative lift of the cam lobe allows the slider arm to pivot and force the timing pin, which in turn allows the latch pin to move. The timing of the hydraulic pressurizing and de-pressurizing of the latch pin is less rigorous than in previous designs. The technical effect of this invention is to improve the timing and control of the latch pin in internal combustion engines.

Problems solved by technology

The timing of the hydraulic pressurizing and de-pressurizing of the latch pin thus is much less rigorous than in the prior art.

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